<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			for(var i=1;i<10;i++){
				for(var j =1;j<=i;j++){
					document.write(i+"*"+j+"="+i*j+"&nbsp;");
				}
				document.write("<br>");
			}
		</script>
		<script>
			var age = 19;
			if(age>18){
				alert("按照中国法律你可以娶媳妇了")
			}else{
				alert("不要这么急着进入坟墓！！")
			}
			
			var username = null;
			if(username){
				alert(username)
			}else{
				alert("张三");
			}
			
			var score = 98;
			switch(Math.floor(score/10)){
				case 10: alert("很优秀了")
				break;
				case 9: alert("很已经很不错了")
				break;
				case 8: alert("确实不错")
				break;
				case 6: alert("我觉得不错")
				break;
				default :alert("你要好好学习了")
			}
			
			var sum = 0;
			var count = 1;
			while(count<=100){
				sum+=count;
				count++
			}
			alert(sum);
		</script>
	</head>
	<body>}
	</body>
</html>
